autoheal(test): fix multi-addon happy path test click pattern (#291)

Fixes master CI failure: Full E2E summary,
E2E-full-Chromium-mobile-admin-shard-2-of-2 on SHA 9c74c4d4 (PR #289).

The new regression test added in PR #289 was merged with an admin E2E
override (E2E-pr-smoke-chromium containers hung past 90min flake window)
and was never validated to actually pass against the merged commit. As a
result, master has been red on the full e2e shard since 14:34 UTC today.

## Root cause

After long-pressing to open the additional-items fullscreen view and
selecting an additional product, the fullscreen view stays open (the
closing branch in `onClickAddProduct` is intentionally commented out).
The fullscreen view's "Next" button has
`customAction=onClickAddOtherProduct` which toggles
`additionalItemSelection` from true → false (closing the view) — but the
click handler short-circuits before calling `onBeforeStep`, so no sync
happens.

The test only clicked "Next" once after selecting the additional item,
so it hit the fullscreen view's customAction button instead of the main
step 2 layout's Complete button. Result: 0 POSTs landed instead of the
expected 4.

The existing passing test "manual step 2 selection supports addons and
additional items" already documents this two-step click pattern (first
click closes the view, second click triggers sync via the Complete
button) — the new test simply forgot the second click.

## Fix

Match the established pattern: first click closes the fullscreen view,
second click lands on the main step 2 layout's Complete button and
triggers `syncCurrentTransactionToOrder` via `onBeforeComplete`. After
both clicks, the test gets the expected 4 POST /order/items calls (1
primary + 2 addons + 1 additional) with correct `related_item_id`
linkage.

- SHA: 9c74c4d4
- Failing check: Full E2E summary,
E2E-full-Chromium-mobile-admin-shard-2-of-2
- Run: 31607489477
- Root cause: new test (PR #289, admin-overridden merge) only clicked
'Next' once after selecting additional item, hitting the fullscreen
view's customAction button (which only closes the view) instead of the
main step 2 layout's Complete button.

Filed by master-autoheal-agent cron.

Co-authored-by: Worktree Fix Verifier <agent@truckwash.local>

tests/e2e/pos-mobile-order-flow.spec.js

@@ -3513,6 +3513,13 @@ test.describe("POS mobile order flow", () => {
       )
       .toEqual([91]);
 
+    // First click closes the additional-items fullscreen view (the
+    // fullscreen "Next" button's customAction toggles additionalItemSelection
+    // from true -> false via onClickAddOtherProduct). The second click lands
+    // on the main step 2 layout's Complete button and triggers
+    // syncCurrentTransactionToOrder via onBeforeComplete.
+    await page.getByTestId("pos-mobile-next-step").click();
+    await expect(page.getByTestId("pos-mobile-step-2")).toBeVisible({ timeout: 10_000 });
     await page.getByTestId("pos-mobile-next-step").click();
 
     // 1 primary + 2 addons + 1 additional = 4 POST /order/items calls.